In the escalators and moving walkways of the type indicated the steps or pallets are traditionally driven by a chain, integral to the pallets, which goes through the entire walkway and is engaged in a toothed axis driven by an electric gear motor. Said motor is in turn driven by a vulcanized pulley constituting the traction of the handrail. These mechanisms are located in one of the ends of the rolling walkway. Other mechanisms necessary to tighten the chain and the handrail will be located at the other end. The turnover of the pallets or steps takes place in these end areas of the handrail, said pallets or steps which go through the entire length of the moving walkway or escalator on the lower part, completing the return path.
In the last few years there have arisen a series of new designs which, particularly in the case of moving walkways, intend to reduce the maximum height of the machine, which is why the conventional drive system needs to be modified.
There exist several solutions which have been chosen according to the concept of moving walkway being used. One of these solutions is detailed in international patent WO 05042392 from Kone Corporation, according to which the drive system is located, at least partially, inside the balustrade, which is possible through the use of a flat motor. Thereafter, the drive occurs through a series of belts or chains which finally drive the pallet chain, which has a short step to be able to turn in the small space available, but it otherwise operates as a conventional chain of a moving walkway.
The U.S. Pat. No. 7,341,139, also from Kone Corporation, describes the drive of a handrail and its joining to the motor system and to the drive of the pallets. The U.S. Pat. No. 7,353,932, from Kone Corporation, describes the arrangement of a pallet belt and the possible use of two driving motors simultaneously.
The Spanish patent 200601651, of Thyssenkrupp, describes a compact walkway based on the concept of a belt formed by pallets of shorter step than the conventional ones. This walkway comprises a drive system which moves the pallets of a moving walkway through drag chains which are directly engaged to the lower part of the traction link chains. The drag chain has separated drag rollers which are made of deformable and elastic materials. The links of the traction chains are connected to one another by joining axes and have teeth and hooks in the lower part for the engagement with the drag chain and the rollers.
In all the aforementioned cases, the drive system includes drag chains which entail a series of problems, such as its lengthening due to use, the need for lubrication, outdoor malfunctioning, difficult maintenance, etc.
As regards escalators, most traction systems are still based on the traditional engagement method between a cogged wheel and a roller chain joined to the steps.